WMBS - dmwm/WMCore GitHub Wiki
WMBS is a relational database which contains most of the operational information of the WMAgent, it is strictly required for the operation of any of the WMComponents and it's absence will trigger a immediate crash in any of them. WMBS makes the WMAgent a state machine in its basic definition.
WMCore supports WMBS with Oracle or MySQL as the DBMS and it most cases they execute the same queries, however some of the queries require different versions according to the DBMS.
Developer note: When writing queries in WMCore for relational databases, try to write a single compatible query for MySQL and Oracle. Exceptions are: Insertions/Deletion/Table creation or cases where using specific features makes the query much more efficient, specially for Oracle which is used for WMAgents handling higher loads.
The tables in WMBS can be divided in four categories: